Integrated Photonics Devices Using Zero-index Metamaterials

We propose an easy-to-implement dual-function on-chip scheme for multi-port phase coherent beam combiner/interferometer, and beam splitter using Zero-Index Metamaterials (ZIM). Such a device can allow efficient coupling between disparate modes in compact geometries with complex bends, which are challenging to achieve using traditional waveguides. Based on the bound states in the continuum, it can greatly eliminate the associated radiation loss, which is common in many existing zero-index implementations due to intrinsic symmetry properties. By using the Finite-Difference Time-Domain method (FDTD), we simulate the on-chip multi-port ZIM combiners at 1550-nm wave-length and the results show that the transmission is normal to output face and there is a good coupling between the input beams in zero-index mode at the designed wavelength, compared to other transmission modes and other wavelengths. By controlling the the phases of the input ports can be adjust to provide the optimal phase coherent output beam, demonstrating its potential as efficient multi-port interferometer. Moreover, when the input ports and the output ports are interchanged, it can be used as beam splitters.